I have absolutely no surprise that the map doesn’t quite depict the range right. I wrote a bit about my process here.

To summarize, though, I’m using ecoregions to form the basis of my mapping. My primary source in deciding whether a species occurs through the Shield, which includes northern MI, WI and MN, is my Ontario checklist. The checklist was published in 1992, and so is probably a little out of date. Added to this is the fact that southern Ontario gets considerably more coverage than northern, so records from the Shield are going to be patchier than down south. And as if that weren’t enough complication, moths are capable of vagrancy, given that they’re equipped with wings.

My Ontario checklist indicated that the only Shield county where the species had been recorded was Thunder Bay. All the rest were southern Ontario counties south of or at the edge of the Shield. The other resource I reference for northern limits is Handfield’s Quebec guide. He likewise only lists its presence in the southern regions, south of the Shield. I checked BugGuide’s records and ButterfliesAndMoths.org’s map, neither of which had records from MI, WI or MN’s Shield country. Covell simply says “…west to WI…” which can be interpreted in a number of ways with regard to the ecoregions.

So what to do with that Thunder Bay record? In the end I tossed it as a vagrant or tiny outlier population, since none of my other data sources supported it.

I have no doubt that this is going to happen for a lot of species. It just wasn’t within the scope of our project to try to collect up records for 21 states and 3 provinces, often scattered or hidden away in drawers in museum collections, much as it would have been nice to have all that data. In an effort to try to balance accuracy with usability, and most of all feasibility, we decided to map using ecoregions as a guide. The landscapes and habitats rarely follow sharp lines, though, especially when it comes to forest types, so I suspect that while these maps will be an indication, they’ll hardly be definitive, and there will be records of species outside the defined range.

Do you know the website eBird? I’m working on developing something similar (though simpler) for moths. Perhaps if the site caught on and people started reporting their observations then if/when the guide went to second edition the range maps could be updated and refined. That’s my hope, anyway.

thanks for the reply Seabrooke. I was just in hopes that a new guide would be more accurate re: the species found in my area. I lack the energy/time to submit all of the records of species I’ve documented or I’d certainly pass them on to you. Good luck with the project.

You and me both, Cindy! Early on, Dave and I had grand plans to make these great, accurate maps. Then we were brought back to reality. I’m sure it would be possible to do, but it would take many years and probably a lot of travel to gather all the necessary data. We’re just not being paid enough for it to be able to afford tracking down the records. Ultimately, we placed the emphasis on making sure there was a good guide available for ID, deciding the ranges weren’t as much the point right now as the live-specimen images were. I still think they’re an improvement over written range descriptions, though.